1 / 17

HVAC 240 Unit 41

HVAC 240 Unit 41. 41.1 Introduction. Troubleshooting ac equipment involves mechanical & electrical systems Symptoms may overlap Technicians must diagnose problems correctly - systematically. 41.2 Mechanical Troubleshooting. Gages & thermometers used when doing mechanical troubleshooting

ezekield
Download Presentation

HVAC 240 Unit 41

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. HVAC 240 Unit 41

  2. 41.1 Introduction • Troubleshooting ac equipment involves mechanical & electrical systems • Symptoms may overlap • Technicians must diagnose problems correctly - systematically

  3. 41.2 Mechanical Troubleshooting • Gages & thermometers used when doing mechanical troubleshooting • R-22 and 410A most common refrigerant used in ac equipment • R-22 t/p chart printed on each gage

  4. Approaching temperature and Temperature difference • Air leaving the evaporator is about 17*-20* cooler than entering • Your split should be 20* for R-22 and 25* for 410A

  5. 41.4 Gage manifold usage • Displays low & high side pressures • Pressures are converted to saturation temps for evaporating refrigerant & condensing refrigerant • Two types of pressure connections: • Schrader valve, Service valve Note:Service valves can be used to isolate the refrigerant

  6. 41.4 When to Connect Gages • Gage manifolds not connected every time system serviced • Small amounts of refrigerant escape each time gages connected • Short gage hoses limit amount of refrigerant loss • Use isolation valve to limit loss- especially on liquid line

  7. 41.4 When to Connect Gages • Gage manifolds not connected every time system serviced • Small amounts of refrigerant escape each time gages connected • Short gage hoses limit amount of refrigerant loss • Use isolation valve to limit loss- especially on liquid line

  8. 41.6 Low Side Gage Readings • Used to compare actual evaporating pressure to normal evaporating pressure • Low side reading verifies refrigerant boiling at correct temp at current load condition • Standard efficiency systems usually have boiling temp ~30-35*F cooler than entering air temp at standard operating condition of 75*F return air with 50% RH • Space temp out of these ranges cause oversized load on evaporator

  9. 41.7 High Side Gage Readings • Used to check relationship of condensing refrigerant to ambient air temperature • Standard air cooled condensers no more than 30*F higher than AA • Check actual outside air temperature • High efficiency condensers operate at lower pressures & condensing temps • TD of 30*

  10. 41.8 Temperature Readings • Useful when checking performance of air conditioning equipment • Temps will vary from system to system • Common temps used for evaluation: Suction-line temperature Condenser outlet-line temperature Compressor discharge-line temperature

  11. Temperature readings 90* summer day readings R22 coil temp 40* or 70psi (low side) condenser temp 125* or 275psi (high side) R410A coil temp 40* or 120psi (low side) condenser temp 125* or 400psi (high side)

  12. 41.9 Charging Procedures in Field Correct charge consists of enough refrigerant in: • Evaporator- Superheat • Suction line • Liquid line • Discharge line • Condenser- Subcooling

  13. 41.9 Charging procedures in field NOTE: under charge will cause high superheat and low subcooling Over charge will cause low superheat and high subcooling

  14. 41.10 Electrical Troubleshooting Volt, Ohms, Amps meter • Tech must know what readings should be • Control voltage stepped down to 24 volts • Begin any electrical troubleshooting by verifying that the power supply is energized • If the power supply voltage is correct, move on to the various components • Checking electrical circuits in parallel should be checked separately

  15. 41.11 Compressor Overload Problems • When compressor overload protector is open, touch motor housing to see if hot • The compressor can be cooled by running cold water over the top of it, ice bag it or by disconnecting it and allowing it to cool cool • Cooling compressor by running water over it may take 30 minutes or longer- usually longer

  16. 41.12 Compressor Electrical Checkup Introduction • Check the motor windings with ohmmeter • Refer to manufacturer's specifications for correct winding resistance values • Compressor may have: Shorted winding Open winding Grounded winding

  17. 41.13 Troubleshooting the Circuit Electrical Protectors – Fuses and Breakers • Compressors & fan motors have protection to guard from minor problems • Do not reset or replace tripped breaker or fuse without determining what caused it to trip or blow

More Related